This invention relates generally to power supplies and more particularly to an integrated buck or boost converter.
Power supplies are known to take one voltage level and convert it to one or more different voltage levels and may be designed using a variety of topologies. For example, a power supply may be a switchboard power supply or ferro-resonance power supply. A switch mode power supply may be implemented using one of many switch-mode topologies. For example, a switch-mode power supply may be implemented as a buck converter, a boost converter, a half-bridge converter, or a full bridge converter.
Typically, if a switch-mode power supply is needed to provide a substantially amount of power (e.g. greater than 100 watts), the power supply will include a full bridge or a half-bridge converter. If a switch-mode power supply is needed for lower power applications, it will include a buck or boost converter. Generally, a buck converter produces an output voltage that is less than the input voltage while a boost converter produces an output voltage that is greater than the input voltage. Thus, in low power applications such as portable electronic devices, a buck or boost converter is generally utilized depending on the voltage of the power source and the voltage needed to power the circuitry of the portable electronic device.
For example, a portable electronic device may be designed to be powered from a lithium battery that produces a supply between 4.2 volts and 3.0 volts while CMOS integrated circuits in the device requiring a supply of 1.8 volts to 2.5 volts. In this example, a buck converter would be utilized to step down the battery voltage to a controlled 1.8 or 2.5 volts. If, however, the same portable electronic device were designed to be powered from a 1xc2xd volt battery, the device would include a boost converter to step up the 1xc2xd volts to 1.8 or 2.5 volts. Clearly, the selection of a power source and the selection of circuitry are made by the designer of the portable electronic device. Therefore, the manufacturing of the integrated circuits should support either choice of the designer of the device can make to power the system.
To minimize the impact of multiple system level designs, many manufacturers implement both a buck and boost converter associated with the same circuitry to provide for flexibility in the choice of power sources. While this technique reduces the complexity of managing multiple system level designs since one design may be used in multiple applications, it requires additional circuitry. As is commonly known, additional circuitry increases the cost to produce a device.
Therefore, a need exists for a single solution that can provide the flexibility to implement either a buck or a boost converter in multiple applications and minimizes the need for additional circuitry.